In a joint, the range of motion depends upon the anatomy of that joint and on the particular genetics of each individual. Typically, joints move in two directions, flexion and extension. Flexion is to bend the joint and extension is to straighten the joint; however, in the orthopedic convention some joints only flex. For example, the ankle has dorsiflexion and plantarflexion. Extension of the ankle would damage that joint. Other joints not only flex and extend, they rotate. The elbow joint, for instance, has supination and pronation which is rotation of the hand about the longitudinal axis of the forearm placing the palm facing up or facing down.
When a joint is injured either by trauma or by surgery, scar tissue can form, often resulting in flexion or extension contractures which can adversely affect the movement of the joint. For example, during supination or pronation of a patient's hand (palm facing upward or downward, respectively), the ulna and radius bones in the lower portion of the arm of the patient move relative to each other. During treatment of a patient for such an injury, it may be desirable to stretch viscoelastic body tissue connected with the ulna and radius bones and/or with the humerus in the arm of a patient in order to obtain a greater range of supination or pronation of the hand of the patient.
Injurious conditions can limit the range of motion of the joint, limiting flexion of the joint (in the case of an extension contracture) or limiting extension of the joint (in the case of a flexion contracture). It is often possible to ameliorate such conditions by use of a range-of-motion (ROM) orthosis. ROM orthosis secure certain bones involved with range of motion (for example, in the forearm) and mechanically induce movement. Such induced movement helps stretch the viscoelastic tissues to give the patient a greater range of mobility. In many instances, the patient can eventually enjoy a full range of movement.
ROM orthoses are devices commonly used during physical rehabilitative therapy to increase the range-of-motion over which the patient can flex or extend the joint. Commercially available ROM orthoses are typically attached on opposite members of the joint and apply a torque to rotate the joint in opposition to the contraction. The force is gradually increased to increase the working range or angle of joint motion. Exemplary orthoses include U.S. Pat. No. 6,599,263, entitled “Shoulder Orthosis;” U.S. Pat. No. 6,113,562, entitled “Shoulder Orthosis;” U.S. Pat. No. 5,848,979, entitled “Orthosis;” U.S. Pat. No. 5,685,830, entitled “Adjustable Orthosis Having One-Piece Connector Section for Flexing;” U.S. Pat. No. 5,611,764, entitled “Method of Increasing Range of Motion;” U.S. Pat. No. 5,503,619, entitled “Orthosis for Bending Wrists;” 5,456,268, entitled “Adjustable Orthosis;” U.S. Pat. No. 5,453,075, entitled “Orthosis with Distraction through Range of Motion;” U.S. Pat. No. 5,395,303, entitled “Orthosis with Distraction through Range of Motion;” U.S. Pat. No. 5,365,947, entitled “Adjustable Orthosis;” U.S. Pat. No. 5,285,773, entitled “Orthosis with Distraction through Range of Motion;” U.S. Pat. No. 5,213,095, entitled “Orthosis with Joint Distraction;” and U.S. Pat. No. 5,167,612, entitled “Adjustable Orthosis,” all to Bonutti and herein are expressly incorporated by reference in their entirety.
What is needed in this art are range of motion devices that can stretch viscoelastic tissues to give the patient a greater range of mobility after an injury due to trauma or from surgery.